Mobile radio communication system

ABSTRACT

A mobile radio communication system having a mobile radio communication network and a mobile radio subscriber appliance, wherein a unit in the network layer of the core network of the mobile radio communication network is configured to transmit to the mobile radio subscriber appliance a first message, based on an occurrence of a predetermined event, with a request for a statement which describes at least one radio characteristic of the mobile radio subscriber appliance.

RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 15/860,282, filed Jan. 2, 2018, entitled “MOBILE RADIOCOMMUNICATION SYSTEM,” which is a continuation of U.S. patentapplication Ser. No. 14/259,113, filed Apr. 22, 2014, entitled “MOBILERADIO COMMUNICATION SYSTEM,” which is a continuation of U.S. patentapplication Ser. No. 13/542,689, filed Jul. 6, 2012, entitled “MOBILERADIO COMMUNICATION SYSTEM,” which is a continuation of U.S. patentapplication Ser. No. 12/504,902, filed Jul. 17, 2009, entitled “MOBILERADIO COMMUNICATION SYSTEM,” which is a continuation of U.S. patentapplication Ser. No. 11/346,997, filed Feb. 3, 2006, entitled “MOBILERADIO COMMUNICATION SYSTEM,” which claims priority to German PatentApplication No. 102005005254.1, filed Feb. 4, 2005, entitled“MOBILFUNK-KOMMUNIKATIONSSYSTEM, VERFAHREN ZUM BETREIBEN EINESMOBILFUNK-KOMMUNIKATIONSSYSTEMS, KERNNETZ-VERMITTLUNGSSCHICHT-EINHEITUND VERFAHREN ZUM BETREIBEN EINER KERNNETZ-VERMITTLUNGSSCHICHT-EINHEIT,”the entire contents and disclosures of which are hereby incorporated byreference in their entireties.

BACKGROUND

In the course of further development of mobile radio communicationsystems, work is currently being undertaken to replace the mobile radiocommunication systems based on the GSM (Global System for MobileCommunications) standard with the more powerful mobile radiocommunication systems based on the UMTS (Universal MobileTelecommunication System} standard.

Since the network coverage achieved using UMTS mobile radio networks,that is to say mobile radio communication systems based on the UMTSstandard, is not yet as far advanced as the network coverage achievedusing the existing GSM mobile radio networks, that is to say mobileradio communication systems based on the GSM standard, it is possible touse UMTS mobile radio networks only in particular geographical areas forcommunication services, while other geographical areas have only GSMmobile radio networks available. Accordingly, the situation may arise inwhich a user of a mobile radio subscriber appliance is using a GSMmobile radio network to use a communication service and moves into thedomain of a UMTS radio cell, that is to say into a geographical area inwhich a UMTS mobile radio network can be used, and, because thereception quality of the UMTS mobile radio network is higher there thanthe reception quality of the GSM mobile radio network, for example, orbecause a higher data rate can be achieved in the communication servicewhen using the UMTS mobile radio network; the user now wishes to use thecommunication service using the UMTS mobile radio network, or becausethe user wishes to use a communication service which is provided only bymeans of the UMTS mobile radio network.

A change of mobile radio network used to provide a communication serviceor to provide a communication link is called inter-system handover ofthe communication service or of the communication link. In the describedcase of a change from a GSM mobile radio network to a UMTS mobile radionetwork, this is specifically inter-system handover from a GERAN (GSMEDGE Radio Access Network; EDGE: Enhanced Data Rates For GSM Evolution)to a UTRAN (Universal Terrestrial Radio Access Network).

When a communication service is provided using a packet-switchedcommunication link, for example when the communication service involvesallowing a user to transmit data between the user's mobile radiosubscriber appliance in the Internet, handover is referred to aspacket-switched handover for the communication service or thecommunication link.

In the case of inter-system handover for a packet-switched communicationlink, that is to say packet-switched inter-system handover, from a GERANto a UTRAN, it is necessary for the UTRAN, that is to say the radioaccess network of the UMTS mobile radio network, to have someinformation specific to the mobile radio subscriber appliance in orderto be able to perform the inter-system handover.

This information is defined in the RRC {Radio Resource Control)container INTER RAT HANDOVER INFO, which contains the RAC (Routing AreaCode) for the mobile radio subscriber appliance and the parameter STARTPS, an input parameter which is stored on the USIM (Universal SubscriberIdentity Module) for the encryption algorithm used in the PS(packet-switched) domain, see 3GPP TS 25.331; 3rd Generation PartnershipProject; Technical Specification Group Radio Access Network; RadioResource Control (RRC); Protocol Specification (Release 5).

This information, which is subsequently called the required information,needs to be available in the UTRAN, that is to say in an RNC (RadioNetwork Controller) for the UTRAN, no later than when a GERAN node, thatis to say a BSC (Base Station Controller) for the GERAN, requests theinter-system handover.

Among the required information, particularly the UTRAN capabilities(parameters specifying the extent to which the mobile radio subscriberappliance is UMTS—compatible) specific to the mobile radio subscriberappliance represent a significant volume of data (compared with theother signaling data).

In the course of the development for performing packet-switchedinter-system handover, carried out as part of the 3GPP (Third GenerationPartnership Project) standardization work, no solution has currentlybeen provided for the problem of transmitting the required information.There are currently two proposals:

1. The mobile radio subscriber appliance transmits the requiredinformation as part of the GMM (GPRS Mobility Management; GPRS: GeneralPacket Radio Service) registration request messages, that is to sayusing an Attach Request message or a Routing Area Update Requestmessage, to the SGSN {Serving GPS Support Node) associated with themobile radio subscriber appliance in the core network of the GSM mobileradio network. The SGSN stores the information and forwards it to theGERAN.

A drawback of this procedure is that the mobile radio subscriberappliance has no information about whether the GSM mobile networksupports packet-switched inter-system handover to a UMTS mobile radionetwork, and the information is therefore always transmitted andforwarded, even if the GSM mobile radio network does not supportpacket-switched inter-system handover to a UMTS mobile radio network. Inaddition, this means that the information is repeatedly transmitted tothe SGSN unnecessarily when the location within the SGSN's territorychanges.

2. The GERAN node, that is to say the BSC associated with the mobileradio subscriber appliance in the GERAN, uses the RLC/MAC signalingradio link to request the required information from the mobile radiosubscriber appliance immediately before the packet-switched inter-systemhandover to the UMTS mobile radio network is carried out.

The mobile radio subscriber appliance transmits the required informationto the GERAN node using the RLC/MAC signaling radio link.

A drawback of this procedure is that the conventional RLC/MAC protocolallows only small volumes of data to be transmitted (25 octets permessage), which is not sufficient for transmitting the requiredinformation. Extending the RLC/MAC protocol so that the mobile radiosubscriber appliance can transmit specific information is involved andcomplex. In addition, the request for the required informationimmediately before the inter-system handover (a just-in-time request)increases the probability that the inter-system handover will fail orthat errors will occur, since a significant delay can arise. Inaddition, this procedure requires the information to be transmittedusing the radio interface upon each inter-system handover, which resultsin significant signaling involvement.

WO 02/01895 A1 discloses a method in which the information about thecompression algorithms supported by a mobile radio subscriber applianceis transmitted to an RNC (Radio Network Controller) when a radio beareris set up;

EP 1494494 A2 discloses a method for handover of a terminal to a UTRANin which a mobile terminal transmits information to the UTRAN whichrelates to handover of circuit-switched communication links, andtransmits no information relating to handover by packet-switchedcommunication links.

SUMMARY OF THE INVENTION

The invention is based on the problem of providing a method, which isimproved over the prior art, for transmitting a mobile radio subscriberappliance's specific information required for inter system handover.

The problem is solved by a mobile radio communication system, a methodfor operation of a mobile radio communication system, a core networknetwork-layer unit and a method for operation of a core networknetwork-layer unit.

The invention provides a mobile radio communication system having amobile radio communication network and a mobile radio subscriberappliance, where the mobile radio communication network has a radioaccess network and a core network. A unit in the network layer of thecore network is configured to transmit to the mobile radio subscriberappliance a first message, based on an occurrence of a predeterminedevent, with a request for a statement which describes at least one radiocharacteristic of the mobile radio subscriber appliance, and the mobileradio subscriber appliance is configured to transmit to the unit asecond message with the statement which describes the at least one radiocharacteristic of the mobile radio subscriber appliance.

The invention also provides a method for operating a mobile radiocommunication system having a mobile radio communication network and amobile radio subscriber appliance, where the mobile radio communicationnetwork has a radio access network and a core network, and where themethod involves a unit in the network layer of the core networktransmitting to the mobile radio subscriber appliance a first message,based on an occurrence of a predetermined event, with a request for astatement which describes at least one radio characteristic of themobile radio subscriber appliance, and the mobile radio subscriberappliance transmitting to the unit a second message with the statementwhich describes the at least one radio characteristic of the mobileradio subscriber appliance.

The invention also provides a core network network-layer unit in amobile radio communication network which has a core network and a radioaccess network, which unit is configured to transmit to the mobile radiosubscriber appliance a first message, based on an occurrence of apredetermined event, with a request for a statement which describes atleast one radio characteristic of a mobile radio subscriber appliance,and to receive a second message, sent by the mobile radio subscriberappliance, with the statement which describes the at least one radiocharacteristic of the mobile radio subscriber appliance.

The invention also provides a method for operating a core networknetwork-layer unit in a mobile radio communication network which has acore network and a radio access network, where the method involves thecore network network-layer unit transmitting to the mobile radiosubscriber appliance a first message, based on an occurrence of apredetermined event, with a request for a statement which describes atleast one radio characteristic of a mobile radio subscriber appliance,and receiving a second message, sent by the mobile radio subscriberappliance, with the statement which describes the at least one radiocharacteristic of the mobile radio subscriber appliance.

Clearly, the request for the statement which describes at least oneradio characteristic of the mobile radio subscriber appliance is made bya unit which is part of a higher layer of the communication layer modelused than the unit used for this on the basis of the prior art, namelythe network layer. In contrast to the prior art, particularly therequest for the statement which describes at least one radiocharacteristic of the mobile radio subscriber appliance is not made by aunit in the radio access network but rather by a unit in the corenetwork. In addition, the request is made only when a predeterminedevent occurs, for example when the mobile radio subscriber applianceregisters in the core network or when it is established that the mobileradio subscriber appliance has moved into a geographical area in which aUMTS mobile radio network is available.

However, the statement which describes at least one radio characteristicof the mobile radio subscriber appliance does not need to be requestedand transmitted whenever the predetermined event occurs, for examplewhenever the mobile radio subscriber appliance registers in the corenetwork, but rather only when the unit in the network layer which isassociated with the mobile radio subscriber appliance changes.

If the mobile radio communication network is a GSM mobile radiocommunication network, for example, that is to say is a mobile radiocommunication network based on the GSM (Global EDGE System for MobileCommunications) standard, and if the unit in the network layer is anSGSN (Serving GPRS Support Node; GPRS: General Packet Radio Service)then the statement is requested and transmitted again only when the SGSNassociated with the mobile radio subscriber appliance has changed(inter-SGSN change).

In this case, particularly the statement which describes at least oneradio characteristic of the mobile radio subscriber appliance is notrequested by the GERAN (GSN EDGE Radio Access Network; EDGE: EnhancedData Rates for GSM Evolution) of the GSM radio communication network,but rather by the core network of the GSM mobile radio communicationnetwork.

In addition. the unit in the network layer requests a statement whichdescribes at least one radio characteristic of the mobile radiosubscriber appliance only when this is necessary, for example when (inthe case of a GSM mobile radio communication network) the GSM mobileradio communication network supports inter-system handover to a UMTSmobile radio communication network.

Since the SGSN associated with the mobile radio subscriber appliancechanges relatively rarely, the radio characteristics of the mobile radiosubscriber appliance are requested and transmitted only relativelyrarely, in comparison with the procedure in which the statement whichdescribes at least one radio characteristic of the mobile radiosubscriber appliance is requested and stored by the GERAN.

The result of what has been said is that using the invention thesignaling involvement for the statement which describes at least oneradio characteristic of the mobile radio subscriber appliance is low incomparison with the prior art, which means that significant advantagesare obtained for the operator of the mobile radio communicationnetwork—in particular the network operator can save costs by using theinvention.

By way of example, the statement which describes at least one radiocharacteristic of the mobile radio subscriber appliance is the radiocharacteristic itself or an index specifying a radio characteristic, forexample including an index specifying the type of mobile radiosubscriber appliance, so that the index can be used to ascertain theradio characteristic or the radio characteristics of the mobile radiosubscriber appliance.

The further refinements of the invention which are described inconnection with the mobile radio communication system apply mutatismutandis also to the method for operation of a mobile radiocommunication system, to the core network network-layer unit and to themethod for operation of a core network network-layer unit.

It is preferred for the predetermined event to be the registration ofthe mobile radio subscriber appliance in the core network.

By way of example, the predetermined event is the initiation of a GPRSAttach procedure by the mobile radio subscriber appliance or theinitiation of a Registration Area Update procedure by the mobile radiosubscriber appliance.

The statement which describes at least one radio characteristic of themobile radio subscriber appliance can thus be transmitted as part of aregistration procedure, so that no additional messages need to betransmitted and the signaling involvement remains low.

It is also preferred for the unit in the network layer also to beconfigured to store the statement which describes at least one radiocharacteristic of the mobile radio subscriber appliance.

It is also preferred for the mobile radio communication system to have afurther mobile radio network having a further radio access network andhaving a further core network, and for the unit in the network layeralso to be configured to transmit to a further unit in the network layerof the further core network the statement which describes at least oneradio characteristic of the mobile radio subscriber appliance uponinter-system handover of the mobile radio subscriber appliance from themobile radio network to the further mobile radio network.

Clearly, the statement which describes at least one radio characteristicof the mobile radio subscriber appliance is transmitted, in the event ofinter-system handover, from the unit in the network layer (of the corenetwork of the mobile radio network from which the inter-system handovertakes place, for example from the SGSN of a GSM mobile radio network) tothe unit in the network layer of the core network of the mobile radionetwork to which the inter-system handover takes place (for example toan SGSN in a UMTS mobile radio network).

Preferably, the further unit in the network layer is configured totransmit to the further radio access network the statement whichdescribes at least one radio characteristic of the mobile radiosubscriber appliance.

Preferably, the further mobile radio communication network is designedon the basis of the UMTS (Universal Mobile Telecommunication System)standard.

Preferably, the mobile radio communication network is also designed onthe basis of the GSM standard.

Clearly. the invention is preferably used for inter-system handover froma GSM mobile radio network to a UMTS mobile radio network.

It is also preferred for the unit in the network layer to be an SGSN.

Preferably, the predetermined event is activation of the mobile radiosubscriber appliance at the SGSN.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference number in different instances in thedescription and the figures may indicate similar or identical items.

FIG. 1 shows a communication system based on an exemplary embodiment ofthe invention.

FIG. 2 shows a message flowchart based on an exemplary embodiment of theinvention.

FIG. 3 shows Table 1 illustrating an information element based on anexemplary embodiment.

FIG. 4 shows Table 2 illustrating an inter-RAT information containerbased on an exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a communication system 100 based on an exemplary embodimentof the invention.

The communication system 100 has a GSM (Global System for MobileCommunications) mobile radio network 101 and a UMTS (Universal MobileTelecommunication System) mobile radio network 102.

A mobile radio subscriber appliance 103 is both GSM compatible and UMTScompatible. That is to say that the mobile radio subscriber appliance103 can set up radio communication links to the GSM mobile radio network101 and can set up radio communication links to the UMTS mobile radionetwork 102.

When a radio communication link has been set up between the mobile radiosubscriber appliance 103 and the GSM mobile radio network, it isprovided by the GSM mobile radio network using a BTS (Base TransceiverStation) 104, a base station in the GSM mobile radio network 101. TheBTS 104 is coupled to a BSC (Base Station Controller) 105 and is managedby it. The BTS 104 and the BSC 105 are part of the GERAN (GSM Edge RadioAccess Network; EDGE: Enhanced Data Rate for GSM Evolution) 106 of theGSM mobile radio network 101. The GERAN 106 is the radio access networkof the GSM mobile radio network 101.

So that the GSM mobile radio network 101 is able to provide, inparticular, packet-switched communication links and packet-switchedcommunication services, for example data transfers to and from theInternet 108, the BSC 105 is coupled to a first SGSN (Serving GPRSSupport Node) 107. The first SGSN 107 is coupled to a first GGSN(Gateway GPRS Support Node) 109, which is coupled to the Internet 108and has the functionality of a gateway.

The first SGSN 107 and the first GGSN 109 are part of the core network110 of the GSM mobile radio network 101.

When a radio communication link has been set up between the mobile radiosubscriber appliance 103 and the UMTS mobile radio network 102, it isprovided by means of a NodeB 111, a UMTS base station. The NodeB 111 ismanaged by an RNC (Radio Network Controller) 112. So that the UMTSmobile radio network 102 is able to provide packet-switchedcommunication links and packet-switched communication services, forexample data transfers to and from the Internet 108, the RNC 112 iscoupled to a second SGSN 113. The second SGSN 113 is coupled to a secondGGSN 114, which in similar fashion to the first GGSN 109 has thefunctionality of a gateway and is coupled to the Internet 108.

The NodeB 111 and the RNC 112 are part of the UTRAN (UniversalTerrestrial Radio Access Network) 115 in the UMTS mobile radio network102. The UTRAN 115 is the radio access network of the UMTS mobile radionetwork 102.

The second SGSN 113 and the second GGSN 114 are part of the core network116 of the UMTS mobile radio network 102.

The first SGSN 107 and the second SGSN 113 are coupled to one another.In one embodiment, the first SGSN 107 and the second SGSN 113 are oneand the same SGSN (shared SGSN).

When a packet-switched communication link has been set up from themobile radio subscriber appliance 103 to the Internet 108, for example,using a radio communication link to the GSM mobile radio network 101, itis possible, if the mobile radio subscriber appliance 103 is in thedomain of the UMTS mobile radio network 102, to clear down the radiocommunication link to the GSM mobile radio network 101, and thepacket-switched communication link can be extended to the UMTS mobileradio network 102 using a radio communication link which has just beenset up. That is to say that it is possible to perform inter-systemhandover of the packet-switched communication link from the GSM mobileradio network 101 to the UMTS mobile radio network 102, or in otherwords inter-system handover of the packet switched communication linkfrom the GERAN 106 to the UTRAN 115.

To be able to perform such inter-system handover, however, it isnecessary for the RNC 112 to have information specific to the mobileradio subscriber appliance 103. By way of example, as in 3GPP TS 25.331;3rd Generation Partnership Project; Technical Specification Group RadioAccess Network; Radio Resource Control (RRC); Protocol Specification(Release 5), section 10.3.3.42 this information is:

Information Element/Group Type and Semantics name Need referencedescription Access stratum MP Enumerated Indicates the release releaseindicator (R99) of the UE according to [35]. The IE also indicates therelease of the RRC transfer syntax supported by theUE CV- Enumerated 13spare values are not_rr c_connection (REL-4. needed. SetupC completeREL-5 REL-6) DL capability with OP Enumerated simultaneous HS- (32 kbps)DSCH configuration 64 kbps. 128 kbps. 384 kbps) PDCP capability MP PDCPcapability 10.3.3.24 RLC capability MP RLC capability 10.3.3.34Transport channel MP Transport capability channel capability 10.3.3.40RF capability FDD OP RF capability, FDD 10.3.3.33 RF capability TDD OPRF capability One“TDD RF TDD capability” entity 10.3.3.33b shall beincluded for every Chip rate capability supported Physical channel MPPhysical capability channel capability 10.3.3.25 UE multi-mode/mum MP UEmulti- RAT capability mode/multi-RAT capability 10.3.3.41 Securingcapability MP Security capability 10.3.3.37 UE positioning MP UEpositioning capability capability 10.3.3.45 Measurement CH- Measurementcapability fdd_re q_sup capability 10.3.3.21

This Information is subsequently called the required information (forinter-system handover).

In the case of the exemplary embodiment explained below, the informationspecific to the mobile radio subscriber appliance 201 which the RNC 205needs to know for inter-system handover between the GERAN 106 and UTRAN115 is transmitted as part of a GPRS Attach to the first SGSN 203 and isforwarded from there to the RNC 205.

FIG. 2 shows a message flowchart 200 based on an exemplary embodiment ofthe invention.

The message flow shown takes place between a mobile radio subscriberappliance 201, a BSC 202, a first SGSN 203, a second SGSN 204 and an RNC205, which are arranged and in form explained with reference to FIG. 1.

It is assumed that a first radio communication link has been set up fromthe mobile radio subscriber appliance 201 to the GSM mobile radionetwork 101.

In step 206, the mobile radio subscriber appliance 201 transmits anAttach Request message 220 to the first SGSN 203, which message containsthe request for a GPRS Attach for the mobile radio subscriber appliance201, that is to say registration of the mobile radio subscriberappliance 201 at the first SGSN 203.

The Attach Request message 220 is a conventional Attach Request messagefor requesting a GPRS Attach and is in form described in 3GPP TS 24.008V6.7.0; 3rd Generation Partnership Project; Technical SpecificationGroup Core Network; Mobile radio interface Layer 3 specification; Corenetwork protocols; Stage 3 (Release 6), for example.

It is assumed that the GPRS Attach for the mobile radio subscriberappliance 201 is successful at the first SGSN 203.

The first SGSN 203 decides whether to request the required informationfrom the mobile radio subscriber appliance 201. By way of example, thefirst SGSN 203 can decide to request the required information from themobile radio subscriber appliance 201 if the GSM mobile radio network101 supports packet-switched inter-system handover, that is to sayinter-system handover of a packet-switched communication link or of apacket-switched communication service to the UMTS mobile radio network.If the GSM mobile radio network 101 does not support packet-switchedinter-system handover to the UMTS mobile radio network 102, then thefirst SGSN 107 will decide not to request the required information fromthe mobile radio subscriber appliance 201. In this example, however, itis assumed that the GSM mobile radio network 101 does supportpacket-switched inter-system handover to the UMTS mobile radio network102.

The first SGSN 203 may also decide, by way of example, to request therequired information from the mobile radio subscriber appliance 201 ifthe mobile radio subscriber appliance 201 is in a geographical area inwhich both the GSM mobile radio network 101 and the UMTS mobile radionetwork 102 can be used using the mobile radio subscriber appliance 103.

In this example, it is assumed that the first SGSN 203 decides torequest the required information from the mobile radio subscriberappliance 201.

In step 207, the first SGSN 203 transmits an Attach Accept message 221to the mobile radio subscriber appliance 201. The first SGSN 203 usesthe Attach Accept message 221 to acknowledge to the mobile radiosubscriber appliance 201 that the GPRS Attach for the mobile radiosubscriber appliance 201 has been successful. In addition, the AttachAccept message 221 contains the request to the mobile radio subscriberappliance 201 for transmission of the required information to the firstSGSN 203.

By way of example, the Attach Accept message 221 is in form explained in3GPP TS 24.008 V6.7.0; 3rd Generation Partnership Project; TechnicalSpecification Group Core Network; Mobile radio interface Layer 3specification; Core network protocols; Stage 3 (Release 6), butadditionally has the specification that the mobile radio subscriberappliance 201 needs to transmit the required information to the firstSGSN 203.

To this end, the Attach Accept message 221 may contain, by way ofexample, an information element (IE) which is in form shown in table 1of FIG. 3 in accordance with some embodiments.

In this context. the value 0 of the parameter UE-RAC indicates that therequired information is not being requested, and the value 1 of theparameter UE-RAC indicates that the required information is beingrequested.

In step 208, the mobile radio subscriber appliance 201 transmits to thefirst SGSN 203 an Attach Complete message 222, which is in similar formto the Attach Complete message described in 3GPP TS 24.008 V6.7.0; 3rdGeneration Partnership Project; Technical Specification Group CoreNetwork; Mobile radio interface Layer 3 specification; Core networkprotocols; Stage 3 (Release 6), but additionally has an inter-RATinformation container containing the required information.

In this embodiment, the inter-RAT information container is aninformation element of type 4 based on GPP with a minimum length of 3octets. The limitation of the maximum length is given by the maximumnumber of octets in an L3 message based on 3GPP, see 3GPP TS 44.006;3^(rd) Generation Partnership Project; Technical Specification Group GSMEDGE Radio Access Network; Mobile Station—Base Station System (MS—BSS)interface; Data Link (DL) layer specification (Release 5). The inter RATinformation container is in form shown in table 2 of FIG. 4 inaccordance with some embodiments.

The “value portion” (see line 3 of table 2) of the inter-RAT informationcontainer is the inter-RAT Handover info as defined in 3GPP TS 25.331;3rd Generation Partnership Project; Technical Specification Group RadioAccess Network; Radio Resource Control (RRC); Protocol Specification(Release 5).

The inter-RAT information container contains the required information.The inter-RAT information container may also contain securityinformation, for example a START PS value, that is to say an inputparameter for the encryption method used, which parameter is intended tobe used after inter-system handover. The inter-RAT information containermay also contain further information, for example prescribedconfiguration information.

The first SGSN 203 stores the required information transmitted to it.

It is assumed that following the successful GPRS Attach from the mobileradio subscriber appliance 201 to the Internet 108 a packet-switchedcommunication link is set up. When setting up the communication link,the SGSN 203 transmits the required information to the BSC 202 in step209.

It is also assumed that the mobile radio subscriber appliance 201 is inthe domain of a UMTS radio cell of the UMTS mobile radio network 102 instep 210, for example the user of the mobile radio subscriber appliance201 has taken the mobile radio subscriber appliance 201 into a UMTSradio cell of the UMTS mobile radio network 102. The mobile radiosubscriber appliance 201 performs radio measurements and measures thereception quality of the UMTS mobile radio network 102 and of the GSMmobile radio network 101 and notifies the BSC 202 of the measurementresults.

In step 21, the BSC 202 takes into account the required information indeciding that the packet-switched communication link which was set up atthe first SGSN 203 after the GPRS Attach for the mobile radio subscriberappliance 201 now needs to be extended using the UMTS mobile radionetwork 102, that is to say that a new packet-switched communicationlink to the Internet 108 needs to be provided using the UMTS mobileradio network 102, and the packet-switched communication link using theGSM mobile radio network needs to be cleared down.

It is thus necessary to perform inter-system handover of thepacket-switched communication link from the GSM mobile radio network 101to the UMTS mobile radio network 102.

By way of example, a decision is made that the packet-switchedcommunication link to the Internet 108 now needs to be provided usingthe UMTS mobile radio network 102, since in this way a higher datatransmission rate is possible than when using the GSM mobile radionetwork 101. The movement of the mobile radio subscriber appliance 103may also mean that the reception quality of the GSM mobile radio network101 has become so poor that the measurement results of the radiomeasurements are taken as a basis for deciding that inter-systemhandover to the UMTS mobile radio network 102 needs to be performed. Inaddition, it is possible that the user of the mobile radio subscriberappliance 201 wishes to use a communication service which can beprovided only using the UMTS mobile radio network 102.

On the basis of the decision that inter-system handover needs to beperformed the BSC 202 sends a first handover request message 223 to theSGSN 203, which is used to request inter-system handover of the existingpacket-switched communication link from the GSM mobile radio network 101to the UMTS mobile radio network 102.

In step 212, the SGSN 203 sends a second handover request message 224 tothe RNC 205, which is used to ask the RNC 205 to make the necessarypreparations for the inter-system handover.

In particular, a second radio communication link needs to be set up fromthe mobile radio subscriber appliance 201 to the UMTS mobile radionetwork 102, so that the packet-switched communication link can in thefuture be provided by means of the second SGSN 113 and the UMTS mobileradio network 102.

It is assumed that a decision is made that the second radiocommunication link needs to be cleared down using the NodeB 111 (forexample because the mobile radio subscriber appliance has moved into thedomain of the NodeB 111).

The second handover request message 224 contains the requiredinformation, which is transmitted to the RNC 205 in this way.

In step 213, the second RNC 205 takes into account the requiredinformation In reserving radio resources for the second radiocommunication link and acknowledges the second handover request message224 using a first acknowledgement message 225.

In step 214, the first SGSN 203 sends a first Handover Command message226 to the BSC 202. The BSC 202, for its part. transmits a secondHandover Command message 227 to the mobile radio subscriber appliance201 In step 215.

In step 216, the mobile radio subscriber appliance transmits a Handovercomplete message 228 to the RNC 205 in order to acknowledge that it isnow using the second radio communication link for the data transmission.

In the embodiment described, the required information is requested bythe first SGSN 203 as part of the GPRS Attach for the mobile radiosubscriber appliance 201 (Attach Accept message 221), and the requiredinformation is also transmitted to the first SGSN 203 as part of theGPRS Attach (Attach Complete message 222).

In another embodiment, the required information is requested andtransmitted, as part of a Routing Area Update. In a similar fashion tothe Attach Request message 220, the mobile radio subscriber appliance201 transmits a Routing Area Update Request message as part of a RoutingArea Update procedure. This is described in 3GPP TS 24.008 V6.7.0; 3rdGeneration Partnership Project; Technical Specification Group CoreNetwork; Mobile radio interface Layer 3 specification; Core networkprotocols; Stage 3 (Release 6). The first SGSN 203 responds to theRouting Area Update Request message with a Routing Area Update Acceptmessage) which is essentially in a form as in 3GPP TS 24.008 V6.7.0; 3rdGeneration Partnership Project; Technical Specification Group CoreNetwork; Mobile radio interface Layer 3 specification; Core-networkprotocols; Stage 3 (Release 6), but in this embodiment contains therequest to the mobile radio subscriber appliance 201 to transmit therequired information to the first SGSN 203.

The mobile radio subscriber appliance 201 then responds with a RoutingArea Update Complete message, which is in the form described in 3GPP TS24.008 V6.7.0; 3rd Generation Partnership Project; TechnicalSpecification Group Core Network; Mobile radio interface Layer 3specification; Core network protocols; Stage 3 (Release 6) butadditionally contains the required information.

In other embodiments, a hybrid form of the procedures described above isused for requesting and transmitting the required information. By way ofexample, the first SGSN 203 requests transmission of the requiredinformation from the mobile radio subscriber appliance using a RoutingArea Accept message, and the mobile radio subscriber appliance 201transmits the required information as part of a GPRS Attach using aRouting Area Update Complete message.

In addition to the required information being requested and transmittedas part of a registration signaling procedure such as a Routing AreaUpdate and a GPRS Attach, the required information may also be requestedand transmitted as part of a different procedure. By way of example, oneembodiment defines a new GMM (GPRS Mobility Management) procedure incomparison with the prior art, which procedure involves the requiredinformation being requested by the first SGSN 203 and being transmittedfrom the mobile radio subscriber appliance 201 to the first SGSN 203.

This new GMM procedure is carried out when a predetermined event occursor when a predetermined criterion has been met. An example of apredetermined event of this type is when the mobile radio subscriberappliance 201 moves into a geographical area in which both the GSMmobile radio network 101 and the UMTS mobile radio network 102 areavailable, that is to say that radio communication links can be set upboth to the GSM mobile radio network 101 and to the UMTS mobile radionetwork 102.

In one embodiment, the mobile radio subscriber appliance receivessignaling determining whether the GSM mobile radio network 101 supportsinter-system handover to the UMTS mobile radio network 102.

By way of example, this is done using an Information Request messagecontaining an information element (IE), for example, which is in theform shown in table 1. The mobile radio subscriber appliance thentransmits in an Information Provision message which has an inter-RATinformation container containing the required information.

In this embodiment, the inter-RAT information container is aninformation element of type 4 based on GPP with a minimum length of 3octets. The limitation of the maximum length is given by the maximumnumber of octets in an L3 message based on 3 GPP, see 3GPP TS 44.006;3rd Generation Partnership Project; Technical Specification Group GSMEDGE Radio Access Network; Mobile Station-Base Station System (MS—BSS)interface; Data link (DL) layer specification (Release 5). The inter-RATinformation container is in the form shown in table 2.

The invention claimed is:
 1. One or more non-transitory,computer-readable media having instructions that, when executed by oneor more processors, cause an apparatus to: identify a request forinter-system handover information received in a routing area updateaccept message; generate a routing area update complete message toinclude an information element to include the requested inter-systemhandover information; and cause the routing area update complete messageto be transmitted to a network.
 2. The one or more non-transitory,computer-readable media of claim 1, wherein the information elementincludes predefined configuration information about a mobile device. 3.The one or more non-transitory, computer-readable media of claim 1,wherein the information element includes security information.
 4. Theone or more non-transitory, computer-readable media of claim 3, whereinthe security information includes a START PS value.
 5. The one or morenon-transitory, computer-readable media of claim 1, wherein theinformation element includes an indication of radio capabilities of theapparatus.
 6. The one or more non-transitory, computer-readable media ofclaim 1, wherein the information element is a type 4 information elementwith a minimum length of three octets.
 7. The one or morenon-transitory, computer-readable media of claim 1, wherein theinformation element is an inter radio access technology informationcontainer information element.
 8. A method comprising: identifying arequest for inter-system handover information received in a routing areaupdate accept message; generating a routing area update complete messageto include an information element to include the requested inter-systemhandover information; and causing the routing area update completemessage to be transmitted to a network.
 9. The method of claim 8,wherein the information element includes predefined configurationinformation about a mobile device.
 10. The method of claim 8, whereinthe information element includes security information.
 11. The method ofclaim 10, wherein the security information includes a START PS value.12. The method of claim 8, wherein the information element includes anindication of radio capabilities of the apparatus.
 13. The method ofclaim 8, wherein the information element is a type 4 information elementwith a minimum length of three octets.
 14. The method of claim 13,wherein the information element has a maximum length of 40 octets. 15.One or more non-transitory, computer-readable media having instructionsthat, when executed by one or more processors, cause a device to:generate a routing area update accept message to include a request forinter-system handover information; cause the routing area update acceptmessage to be transmitted to a mobile radio subscriber appliance; andidentify, in a routing area update complete message received from themobile radio subscriber appliance, an information element that includesthe requested inter-system handover information.
 16. The one or morenon-transitory, computer-readable media of claim 15, wherein theinstructions, when executed, further cause the device to: perform one ormore handover operations based on the inter-system handover information.17. The one or more non-transitory, computer-readable media of claim 16,wherein the information element includes predefined configurationinformation about a mobile device.
 18. The one or more non-transitory,computer-readable media of claim 16, wherein the information elementincludes security information.
 19. The one or more non-transitory,computer-readable media of claim 18, wherein the security informationincludes a START PS value.
 20. The one or more non-transitory,computer-readable media of claim 16, wherein the information elementincludes an indication of radio capabilities of the mobile radiosubscriber appliance.